Characterization of the Promoter Region forflt-1Tyrosine Kinase Gene, A Receptor for Vascular Ehdothelial Growth Factor

Abstract

The flt-1 gene encodes a Vascular Endothelial Growth Factor receptor, (Flt-1), whose expression is restricted to vascular endothelial cells. To characterize the cell type specificity of flt-1 gene expression, we isolated the upstream genomic DNA of the human flt-1 gene and identified a single transcription initiation site 29 bp downstream of a TATA box. DNA sequencing revealed that one TATA box, four GC boxes, nine ETS motifs and one CRE motif were present in the upstream 489 bp region of exon 1. Functional analyses using CAT plasmids in 293E1 cells, which express significant levels of the flt-1 gene, showed that the -229 to +8 region is essential for the cell type-specific expression of this gene. Deletion mutant analysis also pointed to the possible existence of negative and positive regulatory elements in the region -911 to -435, and +8 to +276, respectively. These results suggest that multiple regulatory factors are involved in the transcriptional regulation of the flt-1 gene expression in a cell type-specific, or a more ubiquitous manner.